A Person owns several credit cards. I want the set Person.cards to contain only valid cards, which are not yet expired.
Can I do this annotating the Person.cards field?

@Entity
public class Person {

@id
Integer customerId;

String name;

@OneToMany
@JoinColumn(name = "CUSTOMER_ID")
// where card.exp_date>current_date ???
Set<Card> cards;

}

@Entity
public class Card {

Column(name = "CUSTOMER_ID")
Integer customerId; // the owner's ID

Date exp_date; // expiration date

}

I'm not sure I follow.

So, you're saying the database will contain expired cards, but you want to annotate them out at the object model level, so when we say getCards, only valid cards are returned?

Just map your objects naturally, and provide a method that gets only valid credit cards. That's one way. This could easily be done using the Criteria API. Here's a little tutorial on it if you like:

http://www.thebookonhibernate.com/HiberBookWeb/learn.jsp?tutorial=09howtousethecriteriaapi

Maybe explore @Where.

Cameron,
you understand the situation right.
This is a legacy database ...
What is dangerous in doing this way?
Thanks for the references, though.

Well even if it is not dangerous what you want is a filter. And filtering is not the job of the annotations but the job of queries/criteria.

If you do this filtering by annotations it means that you will never be able to get the expired cards from the database. So you will not be able to delete them through the Person entity.
Moreover if you can't have them in your Person entity it means that you will also not be able to tell the user that one of his cards has expired, no ?

I am new to Hibernate and did not know (though suspended) about existence of @Where annotation. Now I have learned about it and use it and it works well. Actually my application deals not with credit cards but other object, so concerns about access to expired cards do not apply. You guys recommend criteria and filters instead - is it radically different (and better) from the @Where annotation?

Like filters and criteria, @Where is just another tool in your data persistence toolkit.